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Jun 8, 2007

NXT designers deserve a break

Remember the recent discussion on this blog about whether or not it's legitimate to sell building instructions?

A well-designed model can take days (and weeks) to design, build and rebuild.

Creating CAD models with MLCAD, POV-Ray and LPub (2.2.0.2) is tedious, hard to do right and SLOW, SLOW, SLOW! I'm not sure people understand how much time it takes to create accurate and understandable CAD building instructions. Yesterday, I set LPub running on a rather simple robot and it took over two hours! (I have a 1.66 GHz processor) If I only had to run the program once, it might not be so bad, but every modification requires running the entire file again. It's not uncommon to run the instructions 10-12 times before they come out right. Perhaps, if I could use the newer versions, it might be a bit faster, but I can't. After the instructions are "done", Rick tries them out and then I have to address every problem he finds---some of which require significant changes in my MLCAD files.

After the building instructions are ready, then there are programs to write and test, screen shots to take (and retake). Then you need to explain the program. Don't forget, all the building instructions and programming screen shots then need to cropped and assembled in some kind of desktop publishing format. (I use Photoshop and InDesign.)

It's no wonder we don't find many accurate NXT model directions on the Web. They require a LOT of long tedious hours of work. Anyone who takes the time to create good models with accurate and clear building and programming instructions deserves to be paid well for his or her efforts.

This sort of think is why I end up documenting via photographs during disassembly. 'Course, I must admit this isn't sufficient for most publications, but for documenting and allowing others to build your designs, it works pretty well... and takes a LOT less time.

As an author of several BIs, I can easily agree that it is a pain to do. But using LDGlite instead of POV as renderer for Lpub makes things MUCH faster. And I prefer its images to the photorealistic POV ones: they look much more like LEGO BIs...

I understand that people sell theire instructions, but I think that maybe around half (probably a bit less though) is under 18 years old and does NOT have a credit card to order them with so it sin't only pain to make them, but it is pain that alot of us can't buy them. Even though we are willing to pay for them, we can't, THINK OF THE MINORS TOO IF YOU ARE PLANNING TO SELL OUR INSTRUCTIONS! Espcially if it is bot's made with the retail set only etc, remember that the LEGO Mindstorms NXT is targeted against us youngsters (and teens).

There is a serious void of information about the CAD programs for LEGO anywhere. A couple of dated books are still in print and have some useful information--"LEGO Software Power Tools"(Syngress)(Don't use the program on the CD---go to www.ldraw.org for programs....) and "Virtual LEGO" (No Starch Press).

I'm sure Philo knows far more than I do, but if you want to email me your questions, I'd be happy to share my hard-earned experience with you.

Fay and philo, can you give some advice (links, article, etc) on how to generate good BI's?

Difficult to give definitive answers... The books quoted by Fay are a good start, even if they din't include the latest developments. Most of what I use now was patiently learnt by use. My current flow is this one:- Build models with LeoCAD (by far my preferred CAD program). Submodels are built as separate files (up to now LeoCAD doesn't support submodels, but that could change soon). Most instruction stepping is done with LeoCAD tooCable ends and waypoints for LSynth are also inserted, one cable per step to be easily found.- Export all submodels in LDraw format and create a MPD using MLCad.- Edit file to add LSynth commands to create cables, run LSynth.- Render a first BI with LPub and LDGlite renderer. - Fine tune stepping, and add LPub commands to the file to put several steps per page, add callouts and so on. This is by far the most tedious part (numerous pages generations are needed here).- Render the final BIs...

That said, LeoCAD can be used to generate very readable and understandable BIs - though not graphically superb (and missing cable synthesis). The process is much faster and easier. You can see such BIs in my older models, for example my RCX brick sorter.What you see was created as HTML instructions by LeoCAD, with just some editing to match my website graphical chart.

I didn't use Lpub for generating instructions. I didn't even know about it until you mentioned it to me in your email. I used MLCAD and POV-Ray and rendered each image one at a time! You are right, it was labor intensive.May be next time I should use LPub?

If you're using LPub, you can select jpg or png for your output. If you're talking about converting an ldr file to a photo, I don't know. My graphic converter doesn't recognize the ldr format.I just render it in LPub, POV-Ray or LDGlite if I want a model or part picture with a standard format.

If you want to save a picture in MLCad...use the "Snapshot" option in the menu File>Save Picture(s). You can also move the 3D image around before you snap the shot. There is also an option to remove the step number.

Step number? I have NO idea how to do steps in MLCAD. I make a little model, add a step, then add some more parts. Then I render. Does nothing, just shows the complete model. I use MLCAD, L3PAO, and POV-Ray v3.5. Can someone help?

nxtmeef, You're making the models in MLCad correctly. In "edit mode" you add a few parts, then add a step, then a few more parts, add a step, and so on. MLCad always shows you the model completed in this mode.

If you want to view the parts added per step use "view mode". This will allow you to step through the building process using the arrow buttons on the toolbar. When this mode is selected only the first few parts will be shown in the screen until you move to the next step (that adds more parts).

All of this is in the toolbars and the menu options of MLCad.

To produce images of each step...the radio button within the File>Save Picture(s) must be checked. Then, pics of each step are produced and saved in a folder you choose.

On to the other Photo/Instruction renderers...It gets a little complicated. But, the same idea is there...but you will always need step callouts in your MLCad files.

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